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5.2 Release Notes
Red Hat Enterprise Linux 5
Release Notes for Red Hat Enterprise Linux 5.2
Abstract
The Release Notes provide high-level coverage of the improvements and additions that have been implemented in Red Hat Enterprise Linux 5.2. For detailed documentation on all changes to Red Hat Enterprise Linux for the 5.2 update, refer to the Technical Notes.
1. Release Notes Updates
This section contains information about Red Hat Enterprise Linux 5.2 that did not make it into the Release Notes included in the distribution.
1.1. All Architectures
- Thin Provisioning (also known as "virtual provisioning") will be first released with EMC Symmetrix DMX3 and DMX4. Please refer to the EMC Support Matrix and Symmetrix Enginuity code release notes for further details.
dom0
has a system-wide IRQ (interrupt request line) limit of 256, which is consumed as follows:- 3 per physical CPU.
- 1 per guest device (i.e. NIC or block device)
When the IRQ limit is reached, the system will crash. As such, check your IRQ consumption to make sure that the number of guests you create (and their respective block devices) do not exhaust the IRQ limit.To determine how many IRQs you are currently consuming, run the commandgrep Dynamic-irq /proc/interrupts | wc -l
.- In
/etc/multipath.conf
, settingmax_fds
tounlimited
will prevent themultipathd
daemon from starting up properly. As such, you should use a sufficiently high value instead for this setting. - When provisioning guests during installation, theoption will not be available. When this occurs, the system will require an additional entitlement, separate from the entitlement used by
dom0
.To prevent the consumption of additional entitlements for guests, install therhn-virtualization-common
package manually before attempting to register the system to Red Hat Network. virt-manager
should not be left running continuously, as its memory use will grow over time. This could cause memory starvation.As such, you should only usevirt-manager
when needed. When extended use is required, it is advisable to periodically exit and restartvirt-manager
.- Network driver
r8169
updated to add support for the following devices:- RTL8169sb/8110sb
- RTL8169sc/8110sc
- RTL8168b/8111b
- RTL8101e
- RTL8100e
- The crash utility cannot be used to analyze
kdump
-generatedx86_64
vmcores using thexen-syms-[release]
binary of the Red Hat Enterprise Linux 5.2 kernel. To read these types of vmcores, use the commandcrash --xen_phys_start [address] /boot/xen-syms-[version] vmcore
instead.To determine the value of[address]
, run the commandcat /proc/iomem | grep Hypervisor
. Something similar to the following output should appear:3ee00000-3fdfffff : Hypervisor code and data
The[address]
is the first number in the stated range; in this case, it is 3ee00000. - When installing Red Hat Enterprise Linux 5 on a guest, the guest is configured to explicitly use a temporary installation kernel provided by
dom0
. Once installation finishes, it can then use its own bootloader. However, this can only be achieved by forcing the guest's first reboot to be a shutdown.As such, when thebutton appears at the end of the guest installation, clicking it shuts down the guest, but does not reboot it. This is an expected behavior.Note that when you boot the guest after this it will then use its own bootloader. - Running
rpmbuild
on thecompiz
source RPM will fail if any KDE orqt
development packages (for example,qt-devel
) are installed. This is caused by a bug in thecompiz
configuration script.To work around this, remove any KDE orqt
development packages before attempting to build thecompiz
package from its source RPM. - If your system has either ATI Radeon R500 or R600 graphics card equipped,
firstboot
will not run after installation. The system will go directly to the graphical login screen and skipfirstboot
altogether. If you attempt to runfirstboot
manually (i.e. from a failsafe terminal), the X session will crash.This issue is caused by the driver used by the ATI Radeon R500/R600 hardware. The default driver used by these graphics cards are still in technology preview. To work around this, backup your/etc/X11/xorg.conf
file; then, configure X to use the supportedvesa
driver instead using the following command:system-config-display --reconfig --set-driver=vesa
You can now runfirstboot
. To switch back to your old settings, restore your original/etc/X11/xorg.conf
. nfsroot
is fully supported in this update. This allows users to run Red Hat Enterprise Linux 5.2 with its root file system (/
) mounted via NFS.nfsroot
was originally introduced in Red Hat Enterprise Linux 5 as a subset of the Technology Preview feature Stateless Linux. The full implementation of Stateless Linux remains a Technology Preview.At present,nfsroot
has the following restrictions:- Writable directories that hold system files (for example,
/tmp
,/var
, and/etc
) must be replicated for each client and mounted independently with no sharing between clients. To do so, perform the following steps:- Configure the client's root file system to boot in read-only mode. To do so, set
READONLY
toyes
in/etc/sysconfig/readonly-root
. - Run
cat /etc/rwtab
to view a default list of directories and files mounted by each client in the format[type] [path]
.[type]
can be eitherempty
(an empty path),dirs
(a directory tree that is copied, but is empty), orfiles
(a file or directory tree copied intact). - If any other files or directories need to writable but are not in
/etc/rwtab
, list them in the same format (i.e.[type] [path]
) in a file under/etc/rwtab.d/
. You may use any filename for this file.
- SWAP is not supported over NFS.
- SELinux cannot be enabled on
nfsroot
clients. In general, Red Hat does not recommend disabling SELinux. As such, customers must carefully consider the security implications of this action.
- Installing Red Hat Enterprise Linux 5.2 on a system with multiple network interfaces and manually specified IPv6 addresses may result in a partially incorrect networking setup. When this occurs, your IPv6 settings will not be visible on the installed system.To work around this, set
NETWORKING_IPV6
toyes
in/etc/sysconfig/network
. Then, restart your network connection using the commandservice network restart
. - If your system uses the TSC timer, the
gettimeofday
system call may move backwards. This is because of an overflow issue that causes the TSC timer to jump forward significantly in some cases; when this occurs, the TSC timer will correct itself, but will ultimately register a movement backwards in time.This issue is particularly critical for time-sensitive systems, such as those used for transaction systems and databases. As such, if your system needs precision timing, Red Hat strongly recommends that you set the kernel to use another timer (for example, HPET). - The
READ_AHEAD
setting in thecciss
driver is now removed. Thecciss
driver will now use the block layer default of 256. Testing has shown that the settingREAD_AHEAD=1024
did not result in a consistent improvement in performance; in some situations, this setting could also cause the system to hang. - When multiple NFSv4 clients are repeatedly competing for read/write access to the same file on the NFS server, it is possible for one or more of those clients to stall for an indefinite period of time waiting for access. This occurs because the standard delay observed when failing to get an access delegation from the server is long enough for the client who currently owns such delegation to return it to the server and claim it back again.
- If your system has
yum-rhn-plugin-0.5.2-5.el5_1.2
(or an earlier version) installed, you will be unable to upgrade to Red Hat Enterprise Linux 5.2 throughyum update
. To work around this, upgrade youryum-rhn-plugin
to the latest version (usingyum update yum-rhn-plugin
) before runningyum update
. - If your system has an older version of the
gfs2-kmod
package installed but theyum-kmod
package is not installed, upgrading from Red Hat Enterprise Linux 5.1 to 5.2 will fail. To prevent this, install the latest version ofyum-kmod
first (usingyum install yum-kmod
) before runningyum update
. - Thanks to the help of upstream developers and testing customers, the FS-Cache feature has undergone significant changes in line with upstream FS-Cache implementation. Consequently, the technology preview implementation of FS-Cache in this release is now rendered obsolete.As such, Red Hat does not recommend the usage of FS-Cache. Note that FS-Cache will also be likely disabled for the next minor releases.Red Hat will be focusing on further refining this feature as per upstream specifications. Once an acceptable level of invasiveness and compatibility is reached, FS-Cache will then be re-introduced in Red Hat Enterprise Linux.
- Anaconda cannot access more than 8 SmartArray controllers. If your system has more than 8 such controllers equipped, you will only be able to use storage on the first 8 controllers detected. Anaconda will fail when it attempts to open all other controllers (i.e. the 9th controller and above).Note, however, that these devices will still function properly after installation.
- Firefox is now updated to version 3.0. This update features several fixes and enhancements, most notably:
- Set homepages are now loaded correctly when the Firefox browser window is opened.
- Firefox no longer crashes when you search for the string "do".
- Firefox in 64-bit mode now loads the
ext
JavaScript library correctly. In previous versions of Firefox, web-based applications that used this library either took too long to load, or were never loaded at all. - A cross-site scripting flaw was discovered in the way Firefox handled the jar:URI scheme. This flaw made it possible for a malicious web site to conduct a scripting attack against the user. This security issue is now fixed in this update.
- Several flaws were discovered in the way Firefox processed certain malformed content. Web sites that contained such content could cause Firefox to crash or even execute arbitrary code as the user running Firefox. This security issue is now fixed in this update.
- A race condition was discovered in the way Firefox set the
window.location
property on a web page. With this flaw, it was possible for a web page to set an arbitraryReferer
header; this could lead to a cross-site request forgery (CSRF) attack against websites that rely only on theReferer
header. This security issue is now fixed in this update. - Firefox now renders correctly on laptops equipped with external display.
Note, however, that this update of Firefox is not fully backwards compatible with all JavaScripts or Firefox plugins used today.Also, Red Hat has observed that several large commercial web applications have relied on the presence of some cross-site scripting flaws addressed by this Firefox update. These scripting flaws are described in the following links:Consequently, the use of these commercial web applications may result in some loss of functionality. You can observe this in the presence of additional JavaScript errors in the Firefox Error Console ( => ). Red Hat is currently working with the corresponding vendors to address this. - The updated
ixgbe
driver does not support the Intel 82598AT (Copper Pond 10GbE). - Red Hat closely tracks the upstream Open Fabrics Enterprise Distribution (OFED) code base in order to provide a maximal level of enablement for this still evolving technology. As a consequence, Red Hat can only preserve API/ABI compatibility across minor releases to the degree that the upstream project does. This is an exception from the general practice in the development of Red Hat Enterprise Linux.Because of this, applications build on top of the OFED stack (listed below), might require recompilation or even source-level code changes when moving from one minor release of Red Hat Enterprise Linux to a newer one.This generally is not required for other applications, built on the Red Hat Enterprise Linux software stack.The components affected are:
dapl
compat-dapl
ibsim
ibutils
infiniband-diags
libcxgb3
libehca
libibcm
libibcommon
libibmad
libibumad
libibverbs
libipathverbs
libmlx4
libmthca
libnes
librmdacm
libsdp
mpi-selector
mpitests
mstflint
mvapich
mvapich2
ofed-docs
openib
openib-mstflint
openib-perftest
openib-tvflash
openmpi
opensm
perftest
qlvnictools
qperf
rds-tools
(future)
srptools
tvflash
1.2. x86 Architectures
- Recording needs to be manually enabled on Dell M4300 and M6300. To do this, perform the following steps:
- Open
alsamixer
. - Press Tab to togglein the field (located at the upper left part of the menu).
- Press the Space bar.
- To verify that recording is enabled, the text above the
ADCMux
field should displayL R CAPTUR
.
1.3. x86-64 Architectures
- Recording needs to be manually enabled on Dell M4300 and M6300. To do this, perform the following steps:
- Open
alsamixer
. - Press Tab to togglein the field (located at the upper left part of the menu).
- Press the Space bar.
- To verify that recording is enabled, the text above the
ADCMux
field should displayL R CAPTUR
.
- On an IBM T61 laptop, Red Hat recommends that you refrain from clicking the
glxgears
window (whenglxgears
is run). Doing so can lock the system.To prevent this from occurring, disable the tiling feature. To do so, add the following line in theDevice
section of/etc/X11/xorg.conf
:Option "Tiling" "0"
- The distribution version of the release notes stated that crash dumping through
kexec
andkdump
did not function reliably with HP Smart Array controllers. As of general availability, this issue is now resolved.
1.4. PowerPC Architectures
- Recording needs to be manually enabled on Dell M4300 and M6300. To do this, perform the following steps:
- Open
alsamixer
. - Press Tab to togglein the field (located at the upper left part of the menu).
- Press the Space bar.
- To verify that recording is enabled, the text above the
ADCMux
field should displayL R CAPTUR
.
- The
setroubleshootd
daemon no longer exits with a fault the first timesealert
attempts to connect to the daemon.
1.5. ia64 Architecture
- Recording needs to be manually enabled on Dell M4300 and M6300. To do this, perform the following steps:
- Open
alsamixer
. - Press Tab to togglein the field (located at the upper left part of the menu).
- Press the Space bar.
- To verify that recording is enabled, the text above the
ADCMux
field should displayL R CAPTUR
.
- Running
perftest
will fail if different CPU speeds are detected. As such, you should disable CPU speed scaling before runningperftest
. - When the
kdump
kernel is booted, the following error will appear in the boot log:mknod: /tmp/initrd.[numbers]/dev/efirtc: No such file or directory
This error results from a malformed request to create theefirtc
in an incorrect path. However, the device path in question is also created statically in theinitramfs
when thekdump
service is started. As such, the run-time creation of the device node is redundant, harmless, and should not affect the performance ofkdump
. - The distribution version of the release notes stated that crash dumping through
kexec
andkdump
did not function reliably with HP Smart Array controllers. As of general availability, this issue is now resolved. - Some systems may be unable to boot the
kdump
kernel properly. In such cases, use themachvec=dig
kernel parameter.